1. Field of the Invention
The present invention relates to a method of producing opto-electronic cards and printed circuit boards which are adapted to provide for the passive alignment of VCSELs to waveguides. Moreover, the invention relates to opto-electronic cards and printed circuit boards which incorporate structure providing for the passive alignment of VCSELs to waveguides.
Basically, optical waveguides operate with higher ranges of bandwidths than copper circuits which are employed in printed circuit boards, consequently requiring essentially less operating power, while also not being as susceptible to so-called cross-talk which is encountered in such types of printed circuit boards. Ordinarily, in the technology, waveguides have been utilized in connection with transmissions taking place over long distances; however, more recently, as a result of decreasing manufacturing costs and due to the high bandwidths which are achievable with VCSELs (Vertical Cavity Surface Emitting Lasers), such optical waveguides are increasingly employed in LANs (Local Area Networks). These optical waveguides are currently being used to communicate between processor boards, among other applications in industry and commerce.
For instance, the use of commercially available organic multi-mode ribbon waveguides has been demonstrated for a 10-channel bus with 10 Gb data rate, and whereby connection to VCSELs and PINs (opto-electronic photodiodes or devices) are attained through the utilization of micro-machined connectors. These particular types of known multi-mode ribbon waveguides have been successfully laminated onto electronic printed wiring boards (PWBs).
Moreover, opto-electronic printed circuit boards have also been produced by implementing the embossing of a polymer core, in which an optical fiber is attached to VSCELs or PINS and is arranged so as to project downwardly through the printed circuit board to an optical layer located at the center thereof. In effect, the feasibility in the fabrication of waveguides on the surface of printed circuit boards utilizing build-up layers has been demonstrated and proven in the technology, and wherein passive alignment of VSCELs arrays with these waveguides by means of C4-connections (controlled collapse chip connections) has been widely applied.
2. Discussion of the Prior Art
Although the fabrication and methods of providing improved passive alignment schemes between VSCELs and/or PIN arrays or waveguides within electronic build-up layers is basically known in the technology and employed in industry, further improvements thereto are readily contemplatable in order to render the methods and production costs still more economical and efficient.
Amano, et al. U.S. Pat. No. 6,222,967 B1 discloses a packaging for optically coupling one or more optical waveguides of one or more optical elements. This is accomplished utilizing solder for waveguide alignment, as well as employing the surface effects of resins.
Haake, et al. U.S. Pat. No. 6,164,837 is directed to disclosing the effects of mechanical alignment of an optical fiber within an optical package utilizing micro-manipulation and localized heating of solder preforms in order to freeze the precise location of the optical fiber subsequent to completion of the alignment in connection with the optical package.
Hauer, et al. U.S. Pat. No. 6,125,043 discloses a circuit board arrangement having a component mounted thereon through the intermediary of a soldering process and effectuating an automatic passive alignment due to surface tension effects of melted solder.
Beranek, et al. U.S. Pat. No. 5,857,049 discloses an optoelectronic package or module incorporating an opto-electronic device on one plane which is aligned with an optical fiber located on a second plane. Methods of providing the appropriate component alignment are obtained by wetting bond pads, and also through the use of surface tension effects.
Sasaki, et al. U.S. Pat. No. 5,661,831 discloses a self-aligning optical element and an optical waveguide structure with a laser diode array which is solder bonded to a first pad utilizing the surface tension of solder during reflow.
Swirhun, et al. U.S. Pat. Nos. 5,631,988 and 5,420,954 each disclose an optical interconnect which couples multiple fibers to an array of optoelectronic devices. Reliance is placed on alignment pins and components which are aligned with respect to holes by employing lithographically defined solder patterns, and where surface tension is employed for automatically performing the necessary alignments among the various components.
Hahn, et al. U.S. Pat. No. 5,499,3612 discloses a method using flip chip bonding technology for the passive automatic alignment of optical waveguides and photonic devices employing the surface tension phenomena of controlled volumes of material in a liquid form which is positioned on wettable pads.
Randle U.S. Pat. No. 4,89,377 discloses the alignment of an array of optical fibers with optical components, such as waveguides, which are located in a block of insulating material. Disclosed is an array of accurately formed solder pads, containing controlled amounts of solder.
European Patent Publication EP0 1 120 673 A1 discloses an optical package wherein alignment is achieved by positioning a controlled volume of suitable material in liquid form and employing surface tension effects in order to provide for the necessary alignment, with the provision of the required photonic elements, such as SEL lasers and optical waveguides.
Japanese Patent Publication 2000-56189 discloses an improvement in positional alignment of an optical component relative to an optical fiber, wherein the alignment is effected by the surface tension effects of solder bumps. Similarly, Japanese patent publication 2000-22279 discloses an optical element structure in which optical elements and light transmitting paths can be accurately aligned through the arrangement of solder relative to a metal pad and employing tension effects.
Japanese Patent Publication 08-179154 discloses the alignment of an optical waveguide structure which is formed on a substrate with a laser diode array utilizing the surface tension effects of solder during reflow.
Finally, Japanese patent publication 01-140104 discloses the alignment of an array of optical fibers with optical components, such as waveguides, in a block of insulating material, wherein there is provided an array of accurately formed solder pads, and containing controlled amounts of solder.
Although the foregoing publications to various extent collectively disclose alignments between components of opto-electronic devices or modules of the type described herein, none of these provide for nor suggest the improved method and structure concerning the passive alignment of waveguides as set forth by the present invention.